The present invention relates to a flat panel display device having an evacuated envelope with a plurality of internal support walls which extend from the back wall of the envelope to a mosaic screen on the faceplate and form a plurality of parallel channels, and particularly to a faceplate assembly for such a device.
U.S. Pat. No. 4,028,582 to Anderson et al., issued June 7, 1977, entitled "Guided Beam Flat Display Device," and now the subject of reissue application Ser. No. 862,188 filed Dec. 19, 1977, discloses a shadow mask extending across each of the channels and mounted on the internal support walls in spaced relation to the faceplate. Details of the shadow mask structure and how it is mounted on the support walls are not disclosed.
U.S. Pat. No. 4,145,633 to Peters et al. issued Mar. 20, 1979, entitled "Modular Guided Beam Flat Display Device," discloses a shadow mask mounted on the internal support walls and held in place by metal tips which extend from the support walls to the faceplate. A drawback of the Peters et al. structure is the complex retaining structure required to maintain the shadow mask between the metal tips and the support walls.
In copending application of John A van Raalte, Ser. No. 033,966, filed Apr. 27, 1979, entitled "Modular Tube Shadow Mask Support System," assigned to the same assignee as the instant application, there is shown and described a type of flat panel display device having a plurality of internal support walls forming a plurality of channels with a shadow mask in each of the channels. Each of the masks are supported at two oppositely disposed edges by a suspension system disposed on the envelope beyond the screen area. The shadow masks are unrestricted by the support walls. The support system relies on spring biasing means connected to at least one edge of each of the masks, to keep the masks flat during device operation. The van Raalte application does not describe how the suspension system is referenced to the phosphor screen so that the support walls do not interfere with the image area when the device is assembled.
None of the above-identified references show or describe a faceplate structure including a mosaic screen, shadow masks, shadow mask support structure and internal support walls which permits inspection of the faceplate assembly to assure register between the internal support walls and non-imaging areas of the mosaic screen prior to evacuation of the display device.
U.S. Pat. No. 3,735,179 to Kaplan, issued May 22, 1973, entitled "Face Panel Assembly for Color Cathode-Ray Tube," discloses a plurality of indexing posts on the faceplate cooperating with a plurality of notches in the shadow mask to hold the shadow mask in compression. The notch-post structure orients the mask apertures relative to their assigned dot triad on the phosphor screen to prevent lateral displacement of the mask. The notch-post structure also firmly anchors the mask to the faceplate so that mask movement is limited essentially to a displacement along the beam path, i.e., toward the screen, when subjected to thermal expansion. The Kaplan patent does not disclose or suggest a structure which permits movement of the mask perpendicular to both the beam path and the direction of high frequency scan.